[BUG] WebDAV 服务器不兼容 RFC 9110 中的 HTTP 语义（ETag / Preconditions）

[21:15:02] [INFO] [openlist] [GIN] 2026/09/10 - 21:15:02 | 200 | 0s | 127.0.0.1 | OPTIONS "/dav/openlist-local" [21:15:02] [INFO] [openlist] [GIN] 2026/09/10 - 21:15:02 | 207 | 0s | 127.0.0.1 | PROPFIND "/dav/openlist-local" [21:15:14] [WARN] [openlist] failed get /openlist-local/webdav-etag-probe-70f944bf753142f28832e83e4fae2058.txt: failed to get obj: object not found [21:15:14] [INFO] [openlist] ERRO[2026-09-10 21:15:14] HEAD /dav/openlist-local/webdav-etag-probe-70f944bf753142f28832e83e4fae2058.txt object not found [N/A] [INFO] [openlist] failed to get obj [21:15:14] [INFO] [openlist] [GIN] 2026/09/10 - 21:15:14 | 404 | 506.1µs | 127.0.0.1 | HEAD "/dav/openlist-local/webdav-etag-probe-70f944bf753142f28832e83e4fae2058.txt" [21:15:14] [INFO] [openlist] [GIN] 2026/09/10 - 21:15:14 | 201 | 1.59ms | 127.0.0.1 | PUT "/dav/openlist-local/webdav-etag-probe-70f944bf753142f28832e83e4fae2058.txt" [21:15:14] [INFO] [openlist] [GIN] 2026/09/10 - 21:15:14 | 200 | 0s | 127.0.0.1 | GET "/dav/openlist-local/webdav-etag-probe-70f944bf753142f28832e83e4fae2058.txt" [21:15:14] [INFO] [openlist] [GIN] 2026/09/10 - 21:15:14 | 200 | 0s | 127.0.0.1 | HEAD